syr2¶
Computes a rank-2 update of a symmetric matrix.
Description¶
The syr2
routines compute two scalar-vector-vector product add them
and add the result to a matrix, with a symmetric matrix. The
operation is defined as
where:
alpha
is a scalar,A
is ann
-by-n
symmetric matrix,x
andy
are vectors of lengthn
.
API¶
Syntax¶
void syr2(queue &exec_queue,
uplo upper_lower,
std::int64_t n,
T alpha,
buffer<T,1> &x,
std::int64_t incx,
buffer<T,1> &y,
std::int64_t incy,
buffer<T,1> &a,
std::int64_t lda)
syr2
supports the following precisions and devices.
T |
Devices Supported |
---|---|
|
Host, CPU, and GPU |
|
Host, CPU, and GPU |
Input Parameters¶
- exec_queue
The queue where the routine should be executed.
- upper_lower
Specifies whether
A
is upper or lower triangular. See Data Types for more details.- n
Number of columns of
A
. Must be at least zero.- alpha
Scaling factor for the matrix-vector product.
- x
Buffer holding input vector
x
. The buffer must be of size at least (1 + (n
- 1)*abs(incx
)). See Matrix and Vector Storage for more details.- incx
Stride of vector
x
.- y
Buffer holding input/output vector
y
. The buffer must be of size at least (1 + (n
- 1)*abs(incy
)). See Matrix and Vector Storage for more details.- incy
Stride of vector
y
.- a
Buffer holding input matrix
A
. Must have size at leastlda
*n
. See Matrix and Vector Storage for more details.- lda
Leading dimension of matrix
A
. Must be at leastn
, and positive.
Output Parameters¶
- a
Buffer holding the updated upper triangularpart of the symmetric matrix
A
ifupper_lower =upper
, or the updated lower triangular part of thesymmetric matrixA
ifupper_lower =lower
.